Stress makes your body release out two hormones: cortisol and adrenaline. These chemicals put your body into fight-or-flight mode, ratcheting up your energy level and causing your heart to pound and your muscles to tense. Exercise gives you an outlet to release some of that tension (instead of taking it out on your customer or your colleague) and increases your levels of "Feel-good" chemicals called endorphins.
So why don’t you make yourself (and everyone else) a favor and go for a walk on your lunch hour today!